Ignitor apparatus

ABSTRACT

An ignition assembly for lighting another device, such as a main burner (for example, the sampling burner of an atomic absorption spectrophotometer). An electrically heated igniter coil is placed at the edge of the gaseous (fuel and oxidant) stream of the auxiliary igniter burner, and a deflector causes a small part of this gaseous stream to contact the igniter coil. The igniter coil thus remains substantially outside the auxiliary flame thereby avoiding subjecting it to the intense heat of the full auxiliary flame. In operation, the coil is first energized to cause it to heat up, the auxiliary (igniter) burner is then supplied fuel, to cause the deflected part of the gaseous stream and therefore the whole stream to be ignited, which in turn lights the main device (e.g., sampling burner). The system may also be readily automated, so as to minimize manual operations by the user.

United States Patent 3,139,558 6/1964 Lindberg 43l/263X Primary ExaminerEdward G. Favors Attorney-Edward R. Hyde, Jr.

ABSTRACT: An ignition assembly for lighting another device, such as amain burner (for example, the sampling burner of an atomic absorptionspectrophotometer). An electrically heated igniter coil is placed at theedge of the gaseous (fuel and oxi dant) stream of the auxiliary igniterburner, and a deflector causes a small part of this gaseous stream tocontact the igniter coil. The igniter coil thus remains substantiallyoutside the auxiliary flame thereby avoiding subjecting it to theintense heat of the full auxiliary flame. In operation, the coil isfirst energized to cause it to heat up, the auxiliary (igniter) burneris then supplied fuel, to cause the deflected part of the gaseous streamand therefore the whole stream to be ignited, which in turn lights themain device (e.g., sampling burner), The system may also be readilyautomated, so as to minimize manual operations by the user.

ronrron APPARATUS GENERAL DESCRIPTION This invention relates to anigniter for lighting another device, for example, a main burner. Moreparticularly, the invention concerns an igniter of the type which itselfis normally off (as contrasted to a continuously burning pilot light)which temporarily forms an ignition or pilot flame for igniting anotherdevice. Purely for purposes of concreteness and ease of explanation, itwill be assumed that the device ultimately intended to be ignited is amain burner (and in particular one of the type utilized in analyticalinstruments, for example, for generating the sampling flame of an atomicabsorption spectrophotometer).

In general the invention includes an igniter or auxiliary small burnerfrom which a fuel and oxidant mixture issues in a generally jetlikestream, an electrical ignition coil or heating element positionedadjacent or at an edge of such stream, and a small deflecting plate fordeflecting (a relatively small) part of the fuel and oxidant stream toat least part of the igniter coil. In operation the igniter coil isfirst heated, and then the fuel'and oxidant stream initiated so that thesmall deflected part ignites, thereby igniting the entire stream ofgaseous fuel and oxidant, while the ignition coil remains outside themain part of the igniter flame. The igniter flame may then be utilizedto light a main device, such as a sampling burner of the premixed typeutilized in atomic absorption spectroscopy. A major feature of theinvention is the utilization of a small deflector plate in the gasstream from the igniter so as to insure that the heated igniter coillights the stream, without being placed directly in the stream, therebyavoiding undue heating of the igniter coil from combustion of thegaseous fuel and oxidant flame. The use of such a deflector thusprolongs the useful life of the heating igniter coil.

One object of the invention is the provision of an apparatus forigniting another device (e.g., a main burner) by temporarily forming anigniting or auxiliary flame, while insuring that the means for ignitingthis auxiliary flame is not itself subject to substantial heating by theauxiliary flame once it has been lit.

A related object of the invention is the provision of such an ignitionapparatus which insures long life of the (electrically heated) ignitioncoil, so as to insure that the ignition device may be utilized manytimes without risk of failure.

Other objects, features and advantages of the invention will becomeobvious to one skilled in the art upon reading the following detaileddescription of the invention as utilized in an exemplary embodiment forlighting a main burner (for example, the sampling burner of an atomicabsorption spectrophotometer), which exemplary embodiment is shown inthe accompanying drawings, in which:

FIG. I is a plan view of the auxiliary igniter nozzle or burner and theigniting element therefor;

FIG. 2 is a vertical section through the same elements shown in FIG. 1;

fig. 3 is a detail perspective view of the auxiliary igniter nozzle orburner itself; and

FIG; 4 is a partially schematic side view of an entire systemincorporating an ignition device according to the invention.

DESCRIPTION OF EXEMPLARY IGNITION ASSEMBLY In the FIGS. 1 and 2 detailplan and vertical section, respectively, through the parts of theigniter assembly proper, the igniter or auxiliary burner is shown at 10,while the ignition coil assembly therefor is shown at 12. The igniterassembly burner or nozzle may consist of a single piece of, for example,round stainless steel stock, which has been drilled so as to include ahorizontal inlet channel 14 for snugly receiving a tube 16 supplying thefuel in its main full-diameter portion 18. Although the exact dimensionsare in general not critical, it may be noted that both FIGS. 1 and 2 areessentially to scale for an actual embodiment made and satisfactorilytested, and

the dimensions of this embodiment are hereinafter mentioned merely forexemplary purposes. Thus the internal diameter of fuel supply tube 16may be 0.010 inches for use with acetylene gas under pressure ofapproximately ll pounds per square inch and the internal diameter ofchannel 14 was 0.063 inches to snugly receive the similar outer diameterof such tubing. Main portion 18 narrows, as indicated by shoulderportion 20, to a (also generally round in cross section) nozzle portion22 having a reduced external diameter. Tube 16 would normally beintroduced in channel 14 up to a position 24 just beyond shoulderportion 20. Narrower portion 22 of the nozzle has a pair of bores orapertures extending radially therethrough, so as to form a series offour air-induction openings 26, 26', 28 and the hole (not shown)opposite hole 28, communicating with the extension M of channel 14. Whenthe gaseous fuel is flowing (at a relatively rapid rate) through tube 16and therefore channel extension 14', air will be induced through allfour I of the openings (26, 28, etc.) by Venturi action, much in themanner of a conventional Bunsen burner. Therefore when fuel is flowingthrough pipe 16, a relatively rapidly moving mixture of gaseous fuel andair will issue from the flared ortrumpetlike opening 30 of the nozzle.Although the nozzle proper ends (as does of course the flaring portion)30) at a right-hand edge or shoulder portion 32, generally triangularextensions 34 and 36 (compare FIGS. 2 and 3) are either integrallyformed (as shown) or rigidly attached to the lateral edges of surface32. These triangular extensions 34, 36 form a support for a smalldeflector plate 38. In particular deflector plate 38, preferably made ofplatinum,may consist of a main deflector portion 40 and a pair of shortright-angle legs, one of which is seen at 42 in FIG. 2 (and both ofwhichare indicated at 42, 44 in FIG. 1). The small deflecting portion 40 istherefore positioned in the lower part of the gaseous stream from flaredopening 30 of the nozzle, so as to deflect a small part of this lowerportion of the stream generally downwardly as seen in FIG. 2 (andindicated at 72, as later described).

Although the exact dimensions of the igniter assembly are notnecessarily critical, the dimensions of an embodiment actually made andsuccessfully tested are given, purely for exemplary purposes. The entireassembly 10 may be made from a single fifteen-sixteenths /l6 (about0.94) inch long piece of 303 stainless steel, originally in the form ofthree-eighth diameter round stock. The main body portion 18 is thereforeof this diameter, but may carry threads as indicated at 19 on theexterior surface so as to be readily attachable to a convenientsupporting plate or other structure 41, as by nuts 43,45. Afterextending for about 0.41 inches in length (horizontal dimensions ofFIGS. 1 and 2), portion 18 narrows at shoulder 20 to the nozzle portion22 which is also generally cylindrical (i.e., circular cross section)with an outer diameter of one-fourth (0.25) of an inch. The narrowernozzle portion 22 had a length of 0.34 inches from shoulder 20 to itsfront surface 32 with the center of the four holes (26, 28, etc.) beingone-fourth (0.25) of an inch to the left of end surface 32. In theparticular embodiment the diameter of these holes was threethirty-seconds (0.093) of an inch. The conical throat portion 30 wasmade by using a 45 countersink, which drilled front surface 32 to asufficient depth to cause the larger (right-hand) diameter of the throatto reach a 0.16 inch diameter. Of the total distance of 0.25 inches fromthe center of the air-aspirating holes (e.g., 28) to the surface 32, alittle less than 0.05 inch is counted by the half diameter of the hole,about 0.08 inch by the length of the channel 14 and about 0.12 inches bythe generally conical flaring throat portion 30 of the nozzle. Thegenerally triangular supporting bracket extensions 34, 36 had a length(i.e., the horizontal dimension in FIGS. I and 2) to their (extremeright-hand) lower point of about 0.19 inches. These triangularextensions are of course completely open at the top and bottom (seeFIGS. 1 and 3) and have an internal space therebetween of approximately0.18 inches in width (i.e., the vertical dimension in the top view ofFIG. 2). Since their outer surfaces would normally conform to thetubular dimensions of the nozzle portion 22,

these external surfaces of extensions 34, 36 are curved as may best beseen in the elevational detail view of FIG. 3. The maximum thickness ofextensions 34 and 36 is therefore one half of the outer diameter(0.25inches), less the planar width therebetween (0.18) or one half of0.070 inches, equal to 0.035 inches.

The attached deflector 38 may be made of a platinum ribbon of 0.005 inchthickness and a width of 0.040, which has been bent at right angles atboth ends to form legs 42, 44 while leaving a central section 40 of 0.25inch length (the vertical direction of FIG. 1 or the oblique directionof FIG. 3), not counting the thickness (0.005 inch) of each of the legs42, 44. If the upper and lower very narrow portions of triangularextensions 34, 36 have been relieved for about 0.03 inches (as measuredalong surface 32) as indicated in FIG. 2, the lower part of deflector 38will be very near (about 0.02 inches) from the extreme bottom of thefront edge 35 of the oblique surfaces of extensions 34, 36. In otherwords, the bottom of the deflector 38 will be approximately 0.05 inchesabove the bottom of the point of nozzle 32. Since the deflecting part 40of the deflector 38 is at a 45 angle its effective vertical height asseen in FIG. 1 will be .OflOI 2, or somewhat less than 0.03 inches. Itwill therefore directly intercept only about one-tenth of the width ofthe gas stream issuing from flat aperture 30. In this specific exemplaryversion, the deflector 38 would have its upper and lower surfaces aboutequally distant (namely, 0.05 inches each) from the centerline of nozzleportion 22 and its lower surface and would have an effective verticalextent of about 0.028 inches. Since more of the gas will issue near thecenterline than near the edges of the threaded nozzle opening 30, thedeflector actually directly encounters less than onetenth of the totalvolume of gas,-since it directly deflects a part of the stream that ishalf way between the centerline and the edge of the nozzle. However, thepart of the gas stream which passes below the deflector 38 is alsoinfluenced by the deflected gas stream, which tends to follow the angleddeflector surface because of the Coanda effect, so as to cause some ofthis gas to be deflected by the directly deflected gas generallydownwardly in FIG. 2. The total fuel (e.g., acetylene) flow was about140 cc. per minute through the exemplary igniter burner or nozzle 10.

An ignition coil 50 connected at its lower end 52 to a metallic pin 54and at its upper end 56 to the upper surface 58 if a metal housing 60 ispositioned below and to the right of deflector 38 as may best be seen inFIG. 2. An insulating plug or disc 62 centers pin 54 and therefore thelower end of coil 50 within the housing 60, which centering is alsoassisted by the connection of the upper end 56 of the coil in the mannerillustrated. Electrical leads 64, 66 connected to a voltage source andswitch (not shown in FIGS. 1 and 3) energize this assembly 12 (and inparticular ignition coil 50) whenever the switch is closed. Theelectrical ignition assembly 12 may comprise a commercially availableglow plug type of igniter, utilized for example as to initiate thecombustion in model airplane engines. For example, a suitable glow plugis sold by the K & B Manufacturing Corporation, a division of AuroraPlastics Corporation, Downey, Calif, under the designation glow plugtype KB-lL (K & B Drawing No. 0755, revision I dated Jan. 15, 1967).Obviously other glow plugs or even other types of similar ignitiondevices may be utilized instead. A bent bracket 51, rigidly attached tomain supporting plate 41 may be utilized to hold the ignition coilassembly 12, as by providing threaded portion 53 on the upper part ofhousing 60 and a cooperating attaching nut 55.

The operation ofthe igniter assembly itself is relatively simple.Whenever the switch (not shown) closes a circuit through leads 64,66,ignition coil 50 will start to heat up until it reaches a sufficienttemperature to ignite the gases (for example acetylene mixed with theaspirated air) which is issuing from flared nozzle opening 30, and inparticular that part thereof (72) which is deflected downwardly to theupper part of the ignition coil 50 by deflector 38. Preferably theignition coil is allowed some time to heat up before the fuel is turnedon (by means hereinafter disclosed in exemplary form in FIG. 4) to tube16 to avoid contamination of the atmosphere by unburned fuel. Once thedeflected part at 72 of the gas stream has been ignited, the entire gasstream will of course be immediately kindled, resulting in a flamehaving the general shape indicated at 74 in FIG. 2. Flame 74 may then beutilized to ignite any other device 76, for example a main burner, aswill be described in an exemplary complete system according to theinvention immediately hereinafter. It should be noted that once theigniter flame 74 has been kindled, the ignition coil 50 is not subjectedto the intense heat generated by this flame (or more accurately it isexposed only to the extreme edge of the deflected part of the flame).Additionally even the deflector 38 is not exposed to the hottest part ofthe flame, since it is both well off its center and is also sufficientlyclose to the nozzle so as to not be in the hottest part of the flamealong its longitudinal (i.e., horizontal in FIG. 2) portion. Acomparison of FIGS. 1 and 2 will show the relative positioning ofvarious parts of the auxiliary burner or nozzle 10 and ignitor or heater12 in the exemplary embodiment, utilizing the dimensions previouslygiven and a 1 1 pound per square inch fuel pressure (acetylene in normalusage) at extremely narrow inlet tube 16. Since the relative position ofthe glow plug filament or other ignition element 50, the deflector 33and the nozzle opening 30 would vary somewhat with the pressure of thegaseous fuel and the various dimensions of the nozzle parts, and sincethe exact positioning is not highly critical, it is merely mentionedthat the FIG. 1 and FIG. 2 representations are quite close to scalerepresentations of the exemplary embodiments successfully tested. FIG. 3shows more clearly the details of parts 30-44 of the nozzle or auxiliaryburner.

EXEMPLARY ENTIRE SYSTEM INCORPORATING IGNITER FIG. 4 is a partiallyschematic side view of an exemplary complete system including theigniter assembly of the invention. The auxiliary burner or nozzle 10 andits electrical igniting assembly 12 are shown near the middle of theupper part of FIG. 4. These two assemblies may be identical to the oneshown and described in detail with reference to FIGS. i.3, and some ofthe identical elements thereof are referenced in FIG. 4 with the samenumerals. Additional voltage source 68 and switch are shown forenergizing coil 50 through leads 64,66. The exemplary device intended tobe ignited by the igniter assembly 10,12 is indicated near theright-hand side of the figure as a main burner 76. For purposes ofconcreteness and ease of explanation, it will be assumed that it is thetype of analytical burner utilized in, for example, a atomic absorptionspectroscopy in which a gaseous fuel and and a gaseous oxidant aresupplied (for example, by means of tubes 78, 30 respectively) to amixing chamber 82 prior to their leaving the top of the burner as fromone or more long slots on the upper surface 84 of the burner head 86. Ifthe main burner 76 is specifically adapted for atomic absorptionspectroscopy (or flame photometry) means (not shown) would also beprovided for supplying a sample (typically as a nebulized liquidsolution) into the gases in the mixing chamber. A common technique foraccomplishing this is utilizing one of the gases (typiczilly theoxidant) to aspirate a solution of the sample and form a'fine spraytherefrom by means of a nebulizer, so as to cause sample solution sprayor vapor to be mixed with the gases w thin the mixing chamber 82. Anexemplary sampling burner this type (specifically designed for atomicabsorption spectroscopy) is sold by The Perkin-Elmer Corporation of Norwilk, Conn. under part number 303-0110. It is again emphaiized that it ismerely assumed for purposes of concreteness of explanation that theparticular device ignited by flam' 74 is a burner of this type; it isobviously not necessary thatydevice 76 even be a laboratory burner, letalone an atomic 'nbsorption sampling burner. In the exemplary embodimentit s assumed that the fuel for the main burner supplied at 78 ma comefrom a common fuel tube 88 (by means of tube 90), tube 88 beingconnected to a suitable supply of compressed gaseous fuel (for example acommercially available compressed cylinder of, say, acetylene gas,followed by a pressure regulator). The same fuel may be supplied bymeans of branch tube 92 (typically of a smaller diameter) which may beconnected directly to the adjacent end 16' of the very small fuel inlettube 16 to the igniter assembly nozzle 10. The oxidant to the mainburner may be supplied to tube 80 at its schematically illustrated openend 80 from any conventional source of compressed oxidant gas, such as aconventional air compressor (or alternatively from a regulated cylinderof suitable compressed oxidant, including air, nitrous oxide or othersuitable gas).

In the exemplary automated embodiment of the complete system in FIG. 4,three separate solenoid valves control, respectively: the fuel supply(tubing 90,78) to the main burner as at 94; the fuel supply to theigniter assembly as at 96; and the oxidant to the main burner as at 98.For ease of illustration and explanation, each of these electricallyactuated solenoid valves is indicated as having its own energizingsource at 104, 106 and 108, respectively; obviously a single source andparallel leads therefrom are more economical and are preferably used inthe actual embodiment. Each of the main and igniter fuel solenoids 94,96are controlled by relay switches 114,1 16; while solenoid valves 98 iscontrolled by a mechanical switch 118; All the solenoid valves will beclosed except when energized by their respective sources (104, 106, 108)through their respective switches (114, 116, 118). Both of the relayswitches 114 and 116 are closed (so as to open the valves 94,96) by acommon delay relay solenoid 120, which is energized at the same timethat the ignition coil 50 is supplied electrical energy (as by being inseries therewith as illustrated) by closing of switch 70. Delay relaysolenoid 120 will not cause switches 114, '116 to close until, say,about 2 or 3 seconds after switch 70 has been closed. Whenever switch116 is closed, not only will solenoid valve 96 be actuated (i.e.,opened) but two additionally delay solenoids or relays 122 and 124 willalso be supplied energy so as to be actuated after a further delay of,say, a few seconds. Preferably the delay time of solenoid 122 issomewhat greater than the delay time of solenoid 124 (say, 4 and 2seconds, respectively), so that solenoid 124 will open switch 70 beforesolenoid 122 reopens switch 1 16.

A somewhat schematically illustrated mechanical pushbutton linkage 130may be provided for manually closing the switch 70. Specificallywhenever the lower pushbutton end 132 is manually pressed (upwardly in 110.4) by the operator, the upper end 134 of the link 130 willmechanically close switch 70'. At the same time an auxiliary linkage140, the lefthand end of which is connected by pin 136 and loss-motionslot connection 138 to main linkage 130, will be caused to pivot about afulcrum schematically illustrated at 142 so as to cause the right-handend 144 to close switch 118. The main vertical portion of linkage 130 isconstrained (as by conventional tracks, not shown) to move only avertical line in F 16. 4.

OPERATION OF ENTIRE SYSTEM I presses pushbutton 132, switch 70 will beclosed so as to start the heating of igniter coil 50 immediately; andsimultaneously switch 118 will be closed by auxiliary linkage 140 so asto open solenoid valve 98 to allow gaseous oxidant to enter the mixingchamber through tube 8.0 (this will also cause aspiration andnebulization of the sample solution in a sampling type burner 76.).Because of the delay nature of the solenoid 120, neither switches 114'nor 116 will close until igniter coil 50 has had sufficient time (e.g.,2 or 3 seconds) to reach at least the kindling temperature of the fuelutilized. After this delay, solenoid relay will cause closing of both ofswitches 114 and 116. Closing of switch 116 will of course immediatelycause energy source 106 to open the igniter fuel solenoid valve 96(through a path including the coils of further delay solenoids 122 and124, namely via leads 123 and Issuance of the gas through the extremelynarrow tube 16 to the igniter assembly 10 will be almost instantaneous,as will be the ignition of both the deflected portion of the gas at 72and therefore the main portion of the gas resulting in flame 74, aspreviously described. Thus, flame 74 will ignite almost immediately uponactuation of the relay switch 116.

Although relay switch 114 will close simultaneously with switch 116,thereby opening main burner fuel solenoid valve 94 at this same time,there will normally be a short delay (typically a large fraction of asecond) before the main burner gas being introduced at tube 78 fills themixing chamber and starts issuing out of the upper end 84 of the mainburner (along with the already flowing oxidant and sample, if any). Forthis reason no unburnt fuel (e.g,, acetylene) should escape totheatmosphere through the upper end 84 of the main burner, since ignitionflame 74 will be present before such main burner fuel reaches the top ofthe main burner. As soon asthe fuel of the main burner starts leavingthe upper end 84 of the main burner (along with the oxidant that hasalready been supplied to the main burner, and sample solution ifutilized), the main burner flame indicated at 150 will be ignited. Afterthe delay time (e.g., 2 seconds) provided by delay relay or solenoid124, switch 70 will be opened again (either directly by solenoid 124 orby downward movement of linkage 130,134, either expedient being equallyusable in the illustrated exemplary embodiment) so that current will nolonger be supplied to igniter coil 50. Because of the loss-motionconnection supplied by, for example, slot 138, auxiliary linkage 140will not be moved even if main linkage is moved downwardly by solenoid124. Therefore switch 118 remains closed even after delayed solenoid 124has moved the main linkage 130 back to the position shown in FIG. 4. Itmay be noted that linkage 130 is provided with sufficient friction (asby a vertical track or other mechanical means) so as to be stable in anyposition, so as not to move downwardly (and thereby open switch 70)until delayed solenoid 124 moves it downwardly (either directly orthrough switch 70). Opening of switch 70 of course also deenergizessolenoid 120.

Since delayed solenoid 122 has a longer delay period (say, 4 seconds)than that of solenoid 124, switch 116 will momentarily remain closed soas both to insure energizing of solenoid 124 for sufficient time tocause opening of switch 70, and to allow fuel to be supplied throughtube 16 for a further period so as to insure ignition of the main flame150. After this further delay (of say an additional 2 seconds or soafter switch 70 has been opened), delay solenoid 122 will again openswitch 116, thereby closing solenoid valve 96 so as to shut off the fuelin tube 16 to the igniter 116?".16 10, thereby extinguishing the flame74. This completes an ignition cycle.

It should be noted that at the'end of this ignition cycle, bistableswitch 114 will remain closed as will switch 118, so that the mainburner fuel and oxidant solenoid valves 94 and 98, respectively, remainopen, thereby continuing the supply of oxidant and fuel to the mainburner. Thus, all of the elements of P16. 4 return to their originalposition except for these two switches, and their controlled solenoidvalves. A (say, manually actuated) main burner off switch or pushbuttonis provided for turning off the main burner at a later time as desiredby the operator. As schematically illustrated by mechanical linkage 152a single switch or pushbutton may be utilized to simultaneously openswitches 114 and 118, as long as some type of loss-motion connection isprovided to allow switch 118 to be closed (at the beginning of theignition cycle) without causing closing of switch 1 14.

SUMMARY As previously noted concerning the more detailed description ofthe igniter assemblies 10 and 12 in conjunction with FIGS. 1-3, coil 50(and in particular its upper part) is not exposed to the relativelyintense heat of flame 74 during any part of the operation. In additionto the fact that the deflector 38 allows the coil to be substantiallyoutside of the main part of the igniter flame 74, another advantageaccrues from the arrangement utilizing the deflector 38. Because thecoil 50 is not in the main part of the gas stream at the time that thefuel is first introduced through tube 16 Ge, when solenoid valve 96first opens), the cooling effect on coil 50 of the fuel gas during themoment before it actually ignites is also reduced, insuring that thecoil is not cooled by the gas stream below the kindling temperature ofthe fuel and mixture. Thus, if coil 50 were more or less in the main gasstream, it would either have to be of a relatively high thermal capacityor else raised to a temperature substantially above the kindlingtemperature of the igniter fuel and air mixture to insure that the blastof cool gas did not immediately cool it below the kindling temperatureof the igniter gas mixture. Thus, the deflector allows a fast heatingbut cooler running igniter element to be used. In the exemplaryembodiment of a complete system of FIG. 4, it may be noted that theignition coil may be electrically deenergized (by solenoid 124 andswitch 70) as soon as ignition of flame 74 is assured, thereby limitingto a minimum the amount of time that coil 50 is both being electricallyheated and exposed to the (partial) heating efiect of flame 74; whilethe flame 74 can remain on an additional period to insure sufficienttime for lighting the main device (e.g., burner 76). Thus the use of adeflector, as at 38, extends the life of coil 50 not only by insuringthat it is out of the main stream of flame 74 after it is lit, but alsoallowing it to be rapidly heated only just above the ignitiontemperature of the gases (and in the exemplary system, turned off quitesoon thereafter).

Although a single exemplary embodiment of the igniter apparatus (nozzleand heating element assemblies, 10 and 12) and an exemplary manner ofutilizing the invention in a complete system have been disclosed, theinvention is not limited to any of the details of this exemplaryembodiment and exemplary complete system. Rather, the invention isdefined solely by the scope of the appended claims.

What is claimed is:

1. An igniter apparatus for producing a flame for igniting a maindevice, comprising:

means for forming a gaseous stream of mixed fuel and oxidant along alongitudinal axis;

an igniter element positioned immediately adjacent to, but

substantially outside of said gaseous stream;

means for sometimes heating said igniter element to a temperature abovethe kindling temperature of said gaseous stream;

and deflector means comprising a substantially planar surface positionedin a part of said gaseous stream near said igniter element;

said planar surface being at an acute angle to said longitudinal axis ofsaid gaseous stream, and having an effective width as measured in adirection perpendicular to said longitudinal axis of said gaseous streamof only a minor fraction of the width of said gaseous stream, so as todeflect only a minor portion of said gaseous stream toward said igniterelement, so as to cause said minor portion to just contact said igniterelement in a substantially grazing manner;

whereby when said igniter element is heated, said minor portion of saidgaseous stream will be ignited, thereby causing ignition of the entiregaseous stream, without said igniter element being subsequently exposedto any major part of the resulting flame, so as to avoid undesiredsubstantial heating of said igniter element by said flame.

2. An igniter apparatus accordin to claim 1, in which:

said planar surface is substantial y at a 45 angle to said longitudinalaxis of said gaseous stream, so as to cause deflection of said minorportion at generally approximately 45 from said longitudinal axis.

3. An igniter apparatus according to claim 1, in which:

said igniter element comprises a metallic wire in the form of a coil;

igniter housing means are provided which substantially surround all ofsaid igniter coil except for that part which is most closely adjacentsaid gaseous stream, whereby almost all of said igniter coil iscompletely protected from both direct and indirect heating by saidresulting flame;

and said heating means therefor comprises a source of electrical energyand means for connecting said source to said igniter wire.

4. An igniter apparatus according to claim 3, inwhich:

said igniter coil comprises the heating element of a glow plug.

5. An igniter apparatus according to claim 1, in which:

fuel supply control means are provided for turning on and ofi saidgaseous stream;

switch means are provided for turning on and off said heating means forsaid igniter element;

and operating control means are provided for causing said switch meansto turn on said igniter element before said fuel supply means is turnedon;

whereby said igniter element reaches the kindling temperature of saidgaseous stream before said fuel supply is turned on.

6. An igniter apparatus according to claim 5, in which:

said means for forming said gaseous stream comprises means for receivinga gaseous fuel and for sucking ambient air into the gaseous fuel stream;

whereby said fuel supply control means also effectively turns on thegaseous oxidant, when it turns on the fuel.

7. An igniter apparatus according to claim 6, in which:

said fuel supply control means comprises a valve;

said operating control means comprises a first delay means,

operated by said switch means;

and said first delay means is operatively connected to open said valveso as to turn on said fuel only after the delay provided by said firstdelay means.

8. An igniter apparatus according to claim 7, in which:

said first delay means also is operatively connected to the main deviceto place it in operating condition when said igniter fuel supply isturned on;

whereby upon ignition of said igniter flame, said main device is readiedto be ignited thereby.

9. An igniter apparatus according to claim 7, in which:

said first delay means also is operatively connected to actuate a seconddelay means;

and said second delay means is operatively connected to said igniterswitch means to turn off said igniter element after a further delay toavoid unnecessary heating thereof by said heating means.

10. An igniter apparatus according to claim 7, in which:

said first delay means also is operatively connected to actuate a thirddelay means;

and said third delay means is operatively connected to turn off saidfuel supply valve after a substantial further delay, so as toautomatically turn off said igniter assembly flame after it has hadample time to ignite said main device.

1. An igniter apparatus for producing a flame for igniting a maindevice, comprising: means for forming a gaseous stream of mixed fuel andoxidant along a longitudinal axis; an igniter element positionedimmediately adjacent to, but substantially outside of said gaseousstream; means for sometimes heating said igniter element to atemperature above the kindling temperature of said gaseous stream; anddeflector means comprising a substantially planar surface positioned ina part of said gaseous stream near said igniter element; said planarsurface being at an acute angle to said longitudinal axis of saidgaseous stream, and having an effective width as measured in a directionperpendicular to said longitudinal axis of said gaseous stream of only aminor fraction of the width of said gaseous stream, so as to deflectonly a minor portion of said gaseous stream toward said igniter element,so as to cause said minor portion to just contact said igniter elementin a substantially grazing manner; whereby when said igniter element isheated, said minor portion of said gaseous stream will be ignited,thereby causing ignition of the entire gaseous stream, without saidigniter element being subsequently exposed to any major part of theresulting flame, so as to avoid undesired substantial heating of saidigniter element by said flame.
 2. An igniter apparatus according toclaim 1, in which: said planar surface is substantially at a 45* angleto said longitudinal axis of said gaseous stream, so as to causedeflection of said minor portion at generally approximately 45* fromsaid longitudinal axis.
 3. An igniter apparatus according to claim 1, inwhich: said igniter element comprises a metallic wire in the form of acoil; igniter housing means are provided which substantially surroundall of said igniter coil except for that part which is most closelyadjacent said gaseous stream, whereby almost all of said igniter coil iscompletely protected from both direct and indirect heating by saidresulting flame; aNd said heating means therefor comprises a source ofelectrical energy and means for connecting said source to said igniterwire.
 4. An igniter apparatus according to claim 3, in which: saidigniter coil comprises the heating element of a glow plug.
 5. An igniterapparatus according to claim 1, in which: fuel supply control means areprovided for turning on and off said gaseous stream; switch means areprovided for turning on and off said heating means for said igniterelement; and operating control means are provided for causing saidswitch means to turn on said igniter element before said fuel supplymeans is turned on; whereby said igniter element reaches the kindlingtemperature of said gaseous stream before said fuel supply is turned on.6. An igniter apparatus according to claim 5, in which: said means forforming said gaseous stream comprises means for receiving a gaseous fueland for sucking ambient air into the gaseous fuel stream; whereby saidfuel supply control means also effectively turns on the gaseous oxidant,when it turns on the fuel.
 7. An igniter apparatus according to claim 6,in which: said fuel supply control means comprises a valve; saidoperating control means comprises a first delay means, operated by saidswitch means; and said first delay means is operatively connected toopen said valve so as to turn on said fuel only after the delay providedby said first delay means.
 8. An igniter apparatus according to claim 7,in which: said first delay means also is operatively connected to themain device to place it in operating condition when said igniter fuelsupply is turned on; whereby upon ignition of said igniter flame, saidmain device is readied to be ignited thereby.
 9. An igniter apparatusaccording to claim 7, in which: said first delay means also isoperatively connected to actuate a second delay means; and said seconddelay means is operatively connected to said igniter switch means toturn off said igniter element after a further delay to avoid unnecessaryheating thereof by said heating means.
 10. An igniter apparatusaccording to claim 7, in which: said first delay means also isoperatively connected to actuate a third delay means; and said thirddelay means is operatively connected to turn off said fuel supply valveafter a substantial further delay, so as to automatically turn off saidigniter assembly flame after it has had ample time to ignite said maindevice.